import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket=null;
    public TcpEchoServer(int port) throws IOException {
        serverSocket=new ServerSocket(port);
    }
    public void start() throws IOException {
        System.out.println("启动服务器");
        ExecutorService threadPool= Executors.newCachedThreadPool();
        while(true){
            Socket clientSocket= serverSocket.accept();
            /*Thread t=new Thread(()->{
            //    processConnection(clientSocket);
           // }); t.start();
            */
            threadPool.submit(()->{
                processConnection(clientSocket);
            });
        }
    }

    //使用这个方法来处理一个连接
    //这一个连接对应到一个客户端，但是这里可能会涉及到多次交互
    private void processConnection(Socket clientSocket) {
        System.out.printf("[%s:%d]客户端上线",clientSocket.getInetAddress().toString(),clientSocket.getPort());
        //基于上述socket对象与客户端进行通信
        try(InputStream inputStream=clientSocket.getInputStream();
            OutputStream outputStream=clientSocket.getOutputStream()) {
            while(true){
                //1.读取请求
                Scanner scanner=new Scanner(inputStream);
                if(!scanner.hasNext()){
                    System.out.printf("[%s:%d]客户端下线\n",clientSocket.getInetAddress().toString(),clientSocket.getPort());
                    break;
                }
                String request=scanner.next();
                //2.根据请求构造响应
                String response=process(request);
                //3.返回响应
                PrintWriter printWriter=new PrintWriter(outputStream);
                printWriter.println(response);
                printWriter.flush();
                System.out.printf("[%s:%d]req:%s;resp:%s\n",clientSocket.getInetAddress().toString(),clientSocket.getPort(),
                        request,response);
            }
        } catch (IOException e) {
           e.printStackTrace();
        } finally {
            try {
                clientSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public String process(String request){

        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer=new TcpEchoServer(9090);
        tcpEchoServer.start();
    }
}
